As mentioned, if you are experiencing the flashing textures, try disabling reflections in your options. For those that this is still persisting past that, please be sure to update your OS fully as well.
After making sure that your OS is fully updated, we will want to try clearing out the game cache and the Battle.net cache to make sure there isn’t anything that didn’t get updated/cleared with the patch.
Rebuild the Diablo III Cache 1. Navigate to /Applications/Diablo III/Data_D3/PC/MPQs and delete the Cache folder. 2. Then, navigate to Users/Shared/Battle.net/Agent and delete the Agent.db file. 3. Run the Diablo III Launcher and let the game update its files. 4. Press Play when you see Game is up to date